import java.sql.*;

public class Main {
    private static String username;
    private static int resultSet;

    public static void main(String[] args) {
       // m1();
        //m2();
//      m3();
        m4();



    }
//新增
    private static void m1() {
        //键盘录入

        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        //jdbc步骤
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.创建连接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "root");
//            if (connection != null) {
//                System.out.println("连接成功");
//            }
            //3.写sql
            String sql = "select * from user";

            //4.预编译sql
            preparedStatement = connection.prepareStatement(sql);

            //5.执行sql
            resultSet = preparedStatement.executeQuery();

            //6.遍历结果
            while (resultSet.next()) {
                int id = resultSet.getInt(1);
                String name = resultSet.getString(2);
                String pass = resultSet.getString(3);
                System.out.println(id + "----" + name + "----" + pass);
            }


        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            //7.关闭资源
            try {
                if (resultSet != null) {
                    resultSet.close();
                }
                if (preparedStatement != null) {
                    preparedStatement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    private static <Scanner> void m2() {
        //键盘录入
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入要查询用户名：");
        String name = sc.next();


        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;

        //jdbc步骤
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.创建连接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "root");
//            if (connection != null) {
//                System.out.println("连接成功");
//            }
            //3.写sql
            String sql = "select * from user where name like ?";

            preparedStatement = connection.prepareStatement(sql);
            //设置参数
            preparedStatement.setString(1,"%"+name+"%");

            resultSet = preparedStatement.executeQuery();//执行sql


            while(resultSet.next()) {
                int id = resultSet.getInt(1);
                String username = resultSet.getString(2);
                String pass = resultSet.getString(3);
                System.out.println(id+"----"+name+"----"+pass);
            }


        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {

            try {
                if(resultSet != null) {
                    resultSet.close();
                }
                if(preparedStatement != null) {
                    preparedStatement.close();
                }
                if(connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    private static void m3() {
        Connection connection = null;
        PreparedStatement preparedStatement = null;


        //jdbc步骤
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.创建连接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "root");
//            if (connection != null) {
//                System.out.println("连接成功");
//            }
            //3.写sql
            String sql = "insert into user (name,pass) values(?,?)";

            //4.预编译sql
            preparedStatement = connection.prepareStatement(sql);
            //设置参数
            preparedStatement.setString(1,"小明");
            preparedStatement.setString(2,"123456");
            //5.执行增加
            int result = preparedStatement.executeUpdate();

            if (result > 0){
                System.out.println("添加成功");
            }else {
                System.out.println("添加失败");
            }
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            //7.关闭资源
            try {
                if(preparedStatement != null) {
                    preparedStatement.close();
                }
                if(connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }
//修改
    private static void m4() {
        Connection connection = null;
        PreparedStatement preparedStatement = null;


        //jdbc步骤
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.创建连接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "root");
//            if (connection != null) {
//                System.out.println("连接成功");
//            }
            //3.写sql
            String sql = "update user set name = ?,pass = ? where id = ？";

            //4.预编译sql
            preparedStatement = connection.prepareStatement(sql);
            //设置参数
            preparedStatement.setString(1,"王小明");
            preparedStatement.setString(2,"888");
            preparedStatement.setInt(3,7);
            //5.执行增加
            int result = preparedStatement.executeUpdate();

            if (result > 0){
                System.out.println("修改成功");
            }else {
                System.out.println("修改失败");
            }
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            //7.关闭资源
            try {
                if(preparedStatement != null) {
                    preparedStatement.close();
                }
                if(connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    private static void m5() {
        Connection connection = null;
        PreparedStatement preparedStatement = null;


        //jdbc步骤
        //1.加载驱动
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.创建连接
            String url = "jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            connection = DriverManager.getConnection(url, "root", "root");
//            if (connection != null) {
//                System.out.println("连接成功");
//            }
            //3.写sql
            String sql = "delete from user where id = ？";

            //4.预编译sql
            preparedStatement = connection.prepareStatement(sql);
            //设置参数
            preparedStatement.setObject(1,7);

            //5.执行增加
            int result = preparedStatement.executeUpdate();

            if (result > 0){
                System.out.println("删除成功");
            }else {
                System.out.println("删除失败");
            }
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            //7.关闭资源
            try {
                if(preparedStatement != null) {
                    preparedStatement.close();
                }
                if(connection != null) {
                    connection.close();
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }
}

